A null-pointer dereference in the Linux kernel allows local users to assume root privileges. Brad Spengler, who claims first discovery, announced that he will present a corresponding exploit during the course of the day.

Concurrent with Spengler's discovery in mid-October, Earl Chew likewise brought attention to the bug in an lkml.org blog. The bug affects all kernel versions in the 2.6 series and was fixed in the upcoming 2.6.32 RC. So far Red Hat is the only distro providing patches for what is now the CVE-2009-3547 advisory. Users of other distros can apply a workaround that sets the pointer to a value higher than zero, which prevents the exploit. Admins can enter

# cat /proc/sys/vm/mmap_min_addr

to read the current pointer value. If larger than zero, no action need be taken, otherwise use the command

# sysctl -w vm.mmap_min_addr="4096"

to set the value to 4096, for example. The value, however, is only good until the next reboot. To give it a more lasting value, users of Debian or its derivatives should use the following commands:

First indications are that Ubuntu/Kubuntu 9.10 are not affected by the bug, because the initial counter is set to 65535. However, subsequently installed programs such as Wine or Qemu will reset the counter to zero. First tests with Wine installations show this to be evident. The openSUSE distro is potentially the most vulnerable in that the initial counter is also set to zero.

Security-conscious people dig a deep moat with crocodiles around their homes, hide their furniture in back rooms, and only let visitors into the bathroom if they know the secret password. Grsecurity follows a similarly extreme principle.

Ubuntu/Debian NON-EXPERTS: For a quick and easy WORKING fix.....

The article on THIS page was incredibly disappointing because it assumes expert Linux terminal command knowledge. I literally wasted half an hour of my existence trying to figure out what I was doing wrong. Went to the site above, cut/paste x 2, done.

sudo

Alex

Martini1179, try "sudo -i" and then enter those commands.

...and

Martini1179

...and I checked the value and it IS at zero. I have Wine installed.

Terminal commands DO NOT work in Ubuntu Jaunty

Martini1179

The terminal commands for the more permanent don't work in Ubuntu Jaunty. Whatever I do, I get a "permission denied" error, sudo or no sudo. It doesn't even ask for a sudo password.